The appropriate components, such as for example, magnetites, waxes, coagulants, resin latexes, surfactants, and colorants, and processes of the above copending applications may be selected for the present invention in embodiments thereof.
This invention relates to toner processes, and more specifically, to aggregation and coalescence processes. More specifically, the present invention relates in embodiments to methods for the preparation of toner compositions by a chemical process, such as emulsion aggregation wherein latex particles are aggregated with a wax, a crosslinked gel, colorants, and a magnetite in the presence of a coagulant like a polymetal halide, or alternatively a mixture of coagulants, thereafter coalescing to provide toner particles which when developed by an electrographic process generates documents suitable for magnetic image character recognition or MICR.
A number of advantages are associated with the present invention in embodiments thereof including, for example, excellent hot offset, for example above about 210xc2x0 C., and more specifically, from about 210xc2x0 C. to about 230xc2x0 C.; a fusing latitude of from about 20xc2x0 C. to about 35xc2x0 C., wherein fusing latitude refers to a temperature in which, when a developed image is fused, evidences no offset either to the substrate that the image is fused on, referred as xe2x80x9cColdxe2x80x9d offset or an offset on the fuser roll referred as the xe2x80x9cHOTxe2x80x9d offset; a minimum fixing temperature of, for example, about 170xc2x0 C. to about 195xc2x0 C.; and extended photoreceptor life since the toner fusing temperature can be below about 195xc2x0 C., such as from about 175xc2x0 C. to about 190xc2x0 C., as measured.
In U.S. Pat. No. 6,132,924, the disclosure of which is, totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant a latex, and a coagulant, followed by aggregation and coalescence, wherein the coagulant may be a polyaluminum chloride.
In U.S. Pat. No. 6,268,102, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant a latex, and a coagulant, followed by aggregation and coalescence, wherein the coagulant may be a polyaluminum sulfosilicate.
Illustrated in U.S. Pat. No. 5,994,020, the disclosure of which is totally incorporated herein by reference, are toner preparation processes, and more specifically, a process for the preparation of toner comprising
(i) preparing, or providing a colorant dispersion;
(ii) preparing, or providing a functionalized wax dispersion comprised of a functionalized wax contained in a dispersant mixture comprised of a nonionic surfactant, an ionic surfactant, or mixtures thereof;
(iii) shearing the resulting mixture of the functionalized wax dispersion (ii) and the colorant dispersion (i) with a latex or emulsion blend comprised of resin contained in a mixture of an anionic surfactant and a nonionic surfactant;
(iv) heating the resulting sheared blend of (iii) below about the glass transition temperature (Tg) of the resin particles;
(v) optionally adding additional anionic surfactant to the resulting aggregated suspension of (iv) to prevent, or minimize additional particle growth of the resulting electrostatically bound toner size aggregates during coalescence (iv);
(vi) heating the resulting mixture of (v) above about the Tg of the resin; and optionally,
(vii) separating the toner particles.
Magnetic ink printing methods with inks containing magnetic particles are known. For example, there is disclosed in U.S. Pat. No. 3,998,160, the disclosure of which is totally incorporated herein by reference, that various magnetic inks have been used in printing digits, characters, or artistic designs on checks or bank notes. The magnetic ink used for these processes can contain, for example, acicular magnetic particles, such as a magnetite in a fluid medium, and a magnetic coating of ferric oxide, chromium dioxide, or similar materials dispersed in a vehicle comprising binders, and plasticizers. According to the disclosure of the ""160 patent, there is provided a method of printing on a surface with an ink containing acicular magnetic particles in order that the authenticity of the printing can be verified, and wherein a pattern is formed on a carrier with the ink in the wet state, and wherein the particles are subjected to a magnetic aligning process while the ink is on the carrier. Subsequently, the wet ink is transferred to the surface, which transfer is accomplished with substantially aligned particles.
Disclosed in U.S. Pat. No. 4,128,202, the disclosure of which is totally incorporated herein by reference, is a device for transporting a document that has been mutilated or erroneously encoded and wherein there is provided a predetermined area for the receipt of correctly encoded magnetic image character recognition information (MICR). As indicated in this patent, the information is referred to as MICR characters, which characters can appear, for example, at the bottom of personal checks as printed numbers and symbols. These checks have been printed in an ink containing magnetizable particles therein, and when the information contained on the document is to be read, the document is passed through a sorter/reader which first magnetizes the magnetizable particles, and subsequently detects a magnetic field of the symbols resulting from the magnetic retentivity of the ink. The characters and symbols involved, according to the ""202 patent, are generally segregated into three separate fields, the first field being termed a transient field, which contains the appropriate symbols and characters to identify the bank, bank branch, or the issuing source.
In U.S. Pat. No. 5,914,209, the disclosure of which is totally incorporated by reference, there is illustrated a process for preparing MICR toners using a combination of hard and soft magnetites, and lubricating wax and melt mixing with a resin followed by jetting and classifying the blend to provide toner compositions.
In U.S. Pat. No. 4,517,268, the disclosure of which is totally incorporated by reference, there is illustrated a process for preparing MICR toners using styrene copolymers, such as styrene butadiene, in the absence of a lubricating wax by melt mixing in a Banbury apparatus, followed by pulverizing the magnetite and the resin, followed by jetting and classifying to provide, for example, 10 to 12 micron toner size particles which when mixed with an additive package and a carrier provides a developer suitable for using in the Xerox Corporation 9700(copyright).
Further patents relating to MICR processes are U.S. Pat. Nos. 4,859,550; 5,510,221; and 5,034,298, all illustrating, for example, the generation of MICR toners by conventional means such as that described in U.S. Pat. No. 4,517,268.
In U.S. Pat. No. 5,780,190, the disclosure of which is totally incorporated herein by reference, there is disclosed an ionographic process which comprises the generation of a latent image comprised of characters; developing the image with an encapsulated magnetic toner comprised of a core comprised of a polymer and soft magnetite, and wherein the core is encapsulated within a polymeric shell; and subsequently providing the developed image with magnetic ink characters thereon to a reader/sorter device.
In applications requiring MICR capabilities, the toners selected usually contain magnetites having specific properties, an important one of which is a high enough level of remanence or retentivity. Retentivity is a measure of the magnetism left when the magnetite is removed from the magnetic field, i.e., the residual magnetism. Also of value are toners with a high enough retentivity, such that when the characters are read, the magnetites produce a signal strength of equal to greater than about 100 percent. The signal level can vary in proportion to the amount of toner deposited on the document being generated. The signal strength of a toner composition can be measured by using known devices, including the MICR-Mate 1, manufactured by Checkmate Electronics, Inc.
In forming toner compositions for use with reprographic or xerographic print devices, emulsion aggregation processes are known. For example, emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in a number of Xerox patents, the disclosures of which are totally incorporated herein by reference, such as U.S. Pat. Nos. 5,290,654, 5,278,020, 5,308,734, 5,370,963, 5,344,738, 5,403,693, 5,418,108, 5,364,729, and 5,346,797; and also of interest may be U.S. Pat. Nos. 5,348,832; 5,405,728; 5,366,841; 5,496,676; 5,527,658; 5,585,215; 5,650,255; 5,650,256 and 5,501,935; 5,723,253; 5,744,520; 5,763,133; 5,766,818; 5,747,215; 5,827,633; 5,853,944; 5,804,349; 5,840,462; 5,869,215; 5,869,215; 5,863,698; 5,902,710; 5,910,387; 5,916,725; 5,919,595; 5,925,488 and 5,977,210. The components and processes of the Xerox patents can be selected for the present invention in embodiments thereof.
In addition, the following U.S. Patents relate to emulsion aggregation toner processes, the disclosures of which is totally incorporated herein by reference.
U.S. Pat. No. 5,922,501 illustrates a process for the preparation of toner comprising blending an aqueous colorant dispersion and a latex resin emulsion, and which latex resin is generated from a dimeric acrylic acid, an oligomer acrylic acid, or mixtures thereof and a monomer; heating the resulting mixture at a temperature about equal, or below about the glass transition temperature (Tg) of the latex resin to form aggregates; heating the resulting aggregates at a temperature about equal to, or above about the Tg of the latex resin to effect coalescence and fusing of the aggregates; and optionally isolating the toner product, washing, and drying.
U.S. Pat. No. 5,945,245 illustrates a surfactant free process for the preparation of toner comprising heating a mixture of an emulsion latex, a colorant, and an organic complexing agent.
U.S. Pat. No. 5,482,812 illustrates a process for the preparation of toner compositions or toner particles comprising (i) providing an aqueous pigment dispersion comprised of a pigment, an ionic surfactant, and optionally a charge control agent; (ii) providing a wax dispersion comprised of wax, a dispersant comprised of nonionic surfactant, ionic surfactant or mixtures thereof; (iii) shearing a mixture of the wax dispersion and the pigment dispersion with a latex or emulsion blend comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of the ionic surfactant and a nonionic surfactant; (iv) heating the above sheared blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates with a narrow particle size distribution; (v) adding additional ionic surfactant to the aggregated suspension of (iv) to ensure that no, or minimal additional particle growth of the electrostatically bound toner size aggregates occurs on further increasing the temperature to coalesce the aggregates into toner particles (vi); (vi) heating the mixture of (v) with bound aggregates above about or at the Tg of the resin; and optionally (vii) separating the toner particles from the aqueous slurry by filtration and thereafter optionally washing.
U.S. Pat. No. 5,622,806 describes a process for the preparation of toner compositions with controlled particle size comprising (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant in amounts of from about 0.5 to about 10 percent by weight to water, and an optional charge control agent; (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of the ionic surfactant, a nonionic surfactant, and resin particles, thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin, and charge control agent; and (iii) stirring.
It is a feature of the present invention to provide a toner with a number of the advantages illustrated herein, and more specifically, a magnetite containing toner for Magnetic Ink Character Recognition processes by, for example, selecting specific magnetites that provide an acceptable readability signal by a check reader, and wherein the resulting toners possess a sufficient magnetic signal, desirable melt fusing, hot offset, and fusing latitude temperatures, and which toners contain a gel or a crosslinked resin.
It is another feature of the present invention to provide a MICR toner prepared by a chemical process, especially an emulsion aggregation process, wherein the particle morphology can be tailored from, for example, a potato like shape to spherical shape.
It is also a feature of the present invention to provide a MICR toner by emulsion aggregation process thus enabling the incorporation into a toner of needle shape or acicular magnetite particles of about 450 nanometers to about 700 nanometers in size.
It is yet another feature of the present invention to provide a process that is capable of incorporating into toners needle shape or acicular magnetite, which have a coercivity of about 350 oersteds (Oe) which is about 2 to 3 times that of cubic or spherical magnetite, which have a coercivity of about 110 oersteds, to provide an adequate magnetic signal, for example greater then 100 percent, where 100 percent refers, for example, to the nominal signal for readability by a check reader.
In another feature there resides the preparation of a MICR toner by emulsion aggregation processes wherein the amount of acicular magnetite loading is about 23 to about 30 weight percent of toner, or about 45 to about 65 weight percent for either cubic or spherical magnetite to provide an adequate magnetic signal for readability by a check reader.
Also, in another feature there is disclosed a process for preparing a magnetite dispersion comprised of acicular or cubic iron oxide particles in water containing an anionic surfactant or a nonionic surfactant by either ball milling, attrition, polytroning or media milling resulting in iron oxide particle stabilized by the surfactant, and which dispersion is aggregated with latex particles and wax particles to obtain a MICR toner.
In another feature there is disclosed a process for preparing a MICR toner in which the magnetite dispersion comprising acicular iron oxide particles, water and an anionic or a nonionic surfactant, and wherein the iron oxide particle may settle due to the density differences, and therefore, such particles can be redispersed by a stirring, including homogenization to obtain a suitable pigment dispersion for the preparation of MICR toners.